1. Field of the Invention
The present invention relates to an apparatus for inserting thrust metal inserts between a cylinder block and a crankshaft when the crankshaft is mounted on the cylinder block.
2. Discussion of the Prior Art
A cylinder block of an engine has bearing portions for supporting journals of a crankshaft such that the crankshaft is rotatable about the axis of the journals. The crankshaft includes a main journal, and the bearing portion of the cylinder block which engages the main journal has a function of receiving axial thrust forces acting on the crankshaft and axially positioning the crankshaft, as well as receiving radial thrust forces from, the crankshaft. Usually, this bearing portion has grooves formed on the opposite end faces facing respective crank arms of the crankshaft, so that thrust metals are disposed in the grooves. Namely, the thrust metals are interposed between the bearing portion of the cylinder block and the adjacent two crank arms of the crankshaft. Generally, the bearing portion of the cylinder block has a semicircular concave bearing surface whose diameter corresponds to the diameter of the main journal. After the main journal is fitted on this concave bearing surface, a semicircular bearing cap is fitted on the main journal such that the bearing surface of the bearing portion of the cylinder block and the bearing cap cooperate to encircle the main journal of the crankshaft, for rotatably supporting the main journal. Usually, each of the thrust metals used for the main journal consists of two halves in the form of semicircular upper and lower inserts. After the crankshaft is positioned on the cylinder block, with one half of the circumference of the main journal engaging the appropriate bearing portion, one of the two semicircular inserts is inserted into the corresponding semicircular gap defined by the above-indicated groove on each side of the bearing portion facing the appropriate one of the two crank arms. The other semicircular insert is mounted when the bearing cap is fitted on the remaining half of the circumference of the main journal.
Since the thrust metal inserts have a thickness as small as 2 mm or so and since these inserts should be protected from damage, it has been considered difficult to automate the operation of inserting the above-indicated one thrust metal insert into the gap between the bearing portion of the cylinder block and the crank arms of the crankshaft. Conventionally, the insert is pressed into the gap by a worker's thumb while the crankshaft suitably positioned on the cylinder block is rotated about its axis.
The above job of inserting the thin-walled thrust metal inserts into the small gaps is cumbersome and time-consuming, and may injure the worker's thumb if the job continues a long time. Thus, the insertion of the thrust metal inserts is not an easy work, and its automation is desired for labor saving.